You could have gone to a restaurant and talk things a bit, why do these two had to sperg out this bad? They're supposed to come from a more civilized era...
Back in my days, a desolated location had no means of communication by default so the culprits had 2/3 days before Kindaichi caught them. Now you have to carry a signal scrambler with you... Poor murderers, you have to be tech savvy if you want to kill in peace.